seeddevanddormancy.pdf
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Seed Development and Dormancy
Hiro Nonogaki, Associate Professor
Integrative Seed Biology
Oregon State University
Flower
sepal
petal
stigma
stylefilament
ovule
anther
Esau, 1977; Anatomy of Seed Plants
Flower
sepal
petal
stigma
stylefilament
anther
Esau, 1977; Anatomy of Seed Plants
Wild Carrot Flower
Developmental Stages
1 DAP3 DAP
4 DAP6 DAP
7 DAP8 DAP
9 DAP
10 DAP11 DAP
12 DAP13 DAP
14 DAP
15 DAP
16 DAP
17 DAP
18 DAP
19 DAP
20 DAP
21 DAP
22-12
Composite Flowers
21-12
Raven et al., 1999; Biology of Plants
Composite-Type Seeds
embryo
endosperm
pericarp
testa
“Achene”
Tomato Anther
A B
C
D
E
Tomato Pollen Germination
ovule
stigma
Pollen tube
Fertilization
Fertilization
Double Fertilization
Antipodal cells
Central nuclei
Egg cell
Synergid cell
Sperm nuclei Endosperm
Embryo
Embryo and Endosperm
Endosperm
Embryo
Carrot seed
Intact seed Pericarpremoved embryo
endosperm
Fennel Seed
Embryogenesis
Early - Histodifferentiation
These are overlapping phases !
Seed formation
Mid - Enlargement of the cells
Late - Maturation and drying
Developmental Stages
EarlyMid
globular transition heart torpedo maturepre-globular
Buchanan et al, 2000, Biochemistry and Molecular Biology of Plants
Late19.36
Arabidopsis Embryogenesis
Coppersmith JL, Hewitt JR, Nonogaki H, unpublished results
Globular Stage
The fate of cells are already determined !
Hypophysis
Protoderm
Ground meristem
Procambium vascular tissue
parenchyma
root
Buchanan et al, 2000, Biochemistry and Molecular Biology of Plants
epidermal layer
S1S2
S3S4
S5S6
S7
Morphological Maturation
S1 S2 S3 S4 S5 S6 S7
Kristof JR, Nonogaki H, unpublished results
B1 B2 B3 B4 B5 B6 B7
B1 B2B3B4B5B6B7
TW
T W B1 B2 B3 B4 B5 B6 B7
Ger
min
atio
n Po
tent
ial (
%)
B1 B2 B3 B4 B5 B6 B7
cotaxis
100
50
Physiological Maturation
Kristof JR, Nonogaki H, unpublished results
Seed Abortion
•Seed abortion
•Unsuccessful fertilization
•Bee activity
Drought and High Temperature
Concentrated nectar – unattractive to bees
Flower death
Physiological and genetic problem
Overhead misting could help lowering temperature
http://www.ag.ohio-state.edu/~seedsci/vsp02.html
Two to three bulges in ungerminated pollen
One of the bulges germinates
Carrot Pollen Germination
Pollen tube
Seed Abortion
Chaudhury et al., 1997; Proceedings of National Academy of Sciences USA 94: 4223-4228
Onion Seeds
Raven et al., 1999; Biology of Plants, Esau 1977; Anatomy of Seed Plants
Seed Abortion
Ohad et al., 1996; Proceedings of National Academy of Sciences, USA 93: 5319-5324
50% Abortion
100% Normal
Normal Testa Development
Testa development could be separated from embryogenesis
Chaudhury et al., 1997; Proceedings of National Academy of Sciences USA 94: 4223-4228
Lepiniec et al., 2006; Annu. Rev. Plant Biol. 57: 405-430
Viviparous Seeds
Bewley and Black, 1994; Seeds
Developing wheat seeds9.4
Vivipary
Abscisic acid (ABA)
Water 3 µM ABA
Germination inhibitor
Arabidopsis seed
Western et al., 2000, Plant Physiol 122: 345-355
Testa
Testa Pigmentation Mutants
Lepiniec et al., 2006; Annu. Rev. Plant Biol. 57: 405-430
Endothelium layerendospermembryo
(Phenolic compounds)
Proanthocyanidin Synthesis
Wild type
Mutant
Reduction in proanthocyanidin deposition in vacuole
Debeaujon et al., 2001; Plant Cell 13: 853-872
testa
Reduced Dormancy
Maternally inherited
Debeaujon et al., 2001; Plant Cell 13: 853-872
tt12 x WT
WT x tt12WT
tt12
A B C D
Outer cover
Undevelopedembryo
Embryophysiology Combined
Coat-imposed Dormancy
A B C D
Outer cover
Undevelopedembryo
Embryophysiology Combined
Immature Embryo
A B C D
Outer cover
Undevelopedembryo
Embryophysiology Combined
Embryo Dormancy
Induction of Dormancy
5.13
Bewley and Black, 1994; Seeds
Medicago lupulina
R 98FR 3
Dark 4
R, FR 2
R, FR, R, FR 0R, FR, R, FR, R 95
Irradiation Germination (%)
R, FR, R 97
Bewley and Black, 1994; Seeds
Photoreversibility
“Photoreversibility”
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